Most coronavirus cases are transmitted by people without symptoms, the CDC now says

Most coronavirus infections are spread by people who have no symptoms, the US Centers for Disease Control and Prevention said in a new updated guide.

Noah Burger / AP
On Wednesday, October 21, 2020 in San Francisco, a shopkeeper urges customers to wear masks at the Brandy Melville store. As the coronavirus epidemic changes the workplace in San Francisco, the legions of tech workers left behind will be able to work remotely from anywhere. Families have fled to the beautiful suburbs with backyards. Exit has pushed restricted expensive city rent to the lowest of the year. (AP Photo / Noah Burger)

One of the main reasons why the use of masks is so important, the CDC said.

“Most SARS-CoV-2 infections are transmitted by people without symptoms,” the agency said in a section of its website dedicated to explaining the science of how to use a mask to control the spread of the virus.

The CDC and others estimate that more than 50% of all infections are spread from people who do not exhibit symptoms, the guide added Friday.

“This means that at least half of the new infections come from people who are unlikely to be infected for others.”

According to the CDC, 24% of people who infect others with the virus never develop symptoms and another 35% are pre-symptomatic. It also said that other people became infected while experiencing the symptoms.

Peak infections come five days after infection, the agency said on its website. “With these assumptions, trans %% infection spreads when there are no symptoms, but if the fraction of asymptomatic infection is 24% -30% and peak infection is 4-6 days, it can be up to 51% -70%.”

He cites a study published in the National Academy of Sciences Sciences in July and in yet unpublished CDC data. Previously, the health organization did not specify what percentage of infections were spread by people with the symptom.

The agency added, “Infections are mainly caused by infected people coming in contact with respiratory drops when they breathe, talk, cough, sneeze or sing.”

He also says that people spread more drops when they are talking loudly or singing or when they are working harder on themselves.

The CDC said studies show that 40-45% of infected people never develop symptoms.

“People who develop a therapeutic illness have an increased risk of infection just before the onset of symptoms (prostymptomatic infection) and a few days later.”

“Accordingly, the rate of infection peaks when the level of the virus peaks,” the agency noted.

So, people are spreading the virus when they don’t realize they are infected.

Masks can prevent this spread.

Cloth masks can prevent people from breathing out of saliva or small globes that carry the virus. Those particles can fly directly over others, fall to the surface for lifting, or stretch in the air – especially in a closed room.

The CDC has now also said that the mask prevents people from breathing large and small drops that carry the virus.